Why won't my SG3 show up on my PC when connected with USB cable? It shows up on my laptop. I have looked at similar problems in forums but have not found a case where the phone IS recognised by other computers.

It used to work with my PC. I have no idea what changed. When I connect the phone with the USB cable, it makes the duhduh connecting sound. The phone charges and the display shows it connecting as a media device. On my PC, no device shows up. Naturally, I can no longer transfer files by USB. Very frustrating.

My operating system is Windows 7. Any help appreciated (for a not a very PC-savvy soul).